Printed Wiring Board for
Phase Locked Oscillator
Update 4-30-08, updated for Revision A
Update 7-23-09, updated for Revision B
Updated 8-11-09Update information. Add release history.
Updated 12-26-10Update PLL chip support

Printed Wiring Board for Phase Locked Oscillator, size-B
Use your mouse's "right click" and "Save Link" to download:
a.  PWB-PLO rev B, Master Artwork, and Layout, in ExpressPCB software.  Use this to order from Express.
b.  SKPWB-PLO rev C, Schematic, in ExpressPCB software.  Use for reference only.
c.  There is no Parts List, since this is a pwb design, used to create SLIM-PLO-xx.

    The PWB-PLO is a printed wiring board which is designed and layed out to contain a PLL, a VCO, and two buffer amplifiers.  There are two types of PLL loops that can be incorporated.  One, as an active loop with an op amp and a passive loop without an op amp.
    Any ROS style VCO can be used.  Even a +12v VCO can be operated at +10v, which is the nominal input voltage.  Although these PLO's are designed with the Minicircuits ROS style VCOs, many other manufacturer's VCOs will work just as well.
    If an active op amp loop filter is used with a negative supply voltage, it is likely that the control voltage will go negative.  Many VCO's will stop oscillating with a negative control voltage of -0.6 volts or greater.  This will cause the PLL loop to "hang".  To prevent this situation, a "protection" diode, D1, is installed on the control voltage line.  The voltage will never go less than -0.4 volts.  This will assure that the VCO will continue to oscillate.  This diode must be deleted for all other configurations.
    If a VCO requires +10 volts, the Regulator U5 is not installed.  It is bypassed with a jumper wire or a zero ohm resistor.
Updated 12-26-10. These PLL chips are supported:
The LMX2326 is the original design but has now become obsolete. The ADF4118 is a "drop-in" replacement. The ADF4112 or ADF4113 is an option, requiring the use of R23 (4.7 Kohm).  The LMX2326 or
ADF4118 does not require R23.
    RF energy from the VCO is divided, 3 ways.  The VCO output power level depends on the VCO used.  The Minicircuits ROS-2150VW and ROS-1500 output a minimum of +5 dBm.  One leg of the divider returns to the PLL for reference locking.  We would like a level of -5 dBm to -10 dBm to drive the PLL chip.  The other two legs are amplified by U7 and U8 MMIC amplifiers.  They can be a variety of MMICs.  I have chosen the Minicircuits ERA-33 because I am using it in the I.F. Amplifier SLIM and quantity purchases keep the cost low.  The level of RF output is determined by several factors.  VCO type, the amount of resistive attenuation in the 3-way splitter, the MMIC amplifier used, and the
amount of resistive attenuation placed in the output paths.  The typical maximum output is +13 dBm.
    When the PLO is used as a wide band frequency source to drive the LO port of a mixer, the buffer amplifiers are operated in, or close to, saturation.  This may seem like a bad idea, but it does two things.  First, the output level will have minimum ripple across it's frequency range.  Second, the non-harmonically related, spurious signals will less than if the linear mode.  Normal harmonics will be higher, but, as a local oscillator for mixers, it doesn't matter.  I have tested with both the Sirenza SGA-4586 and the Minicircuits ERA-33SM.  The ERA-33 compression level is a little "flatter" than the SGA-4586.  If linear operation is desired, the resistor divider (R8-R11) could be modified for lower output.
    Presently, there are 2 SLIM PLO's that are designed using this PWB: SLIM-PLO-1, and 
SLIM-PLO-2.  I can see these suffixes growing, as different PLO's are configured and built.  PLO's with any frequency range, up to 3000 MHz, can be configured from this Base Design.  At one time there was a SLIM-PLO-3 but it is discontinued.

Release History
Original Release: Released 7-01-2007
PWB: PWB-PLO Rev 0, archived
Schematic: SKPWB-PLO Rev 0, released
7-01-2007, archived

Revision A: Released 4-26-2008
PWB: PWB-PLO Rev A, archived
Schematic: SKPWB-PLO Rev A, released 
4-26-2008, archived
Revision A:
1.  Revision A changes the R8-R11 VCO power divider.  The new topology adds about 10 dB more isolation between the buffer amplifiers.  It also decreases the drive to the buffers.
2.  Revison A removes the optional component path under U5.  This was a potential short circuit.
3.  Revision A changes the input ferite beads to resistors, to allow for better power supply filtering.
4.  Revision A adds R26, for better VCO noise performance.
The previous board, Rev 0, should be modified for these changes.  Change 1 requires a trace removal to allow repositioning of the R8-R11 change.  Change 2 also requires a trace removal.
Revision A also changes the pad sizes for the electrolytic capacitors so that ceramics can be used as alternate parts.

Revised schematic, 6-11-2008, delete values to make schematic generic.
Schematic: SKPWB-PLO Rev B, archived

Revision B: Released 7-23-2009
Schematic: SKPWB-PLO Rev C
Revision B adds a feedback capacitor to the PLL Loop, C48.  The Master Layout Artwork was revised to accommodate the new capacitor.  Previous revisions of the PWB can be easily modified to allow addition of C48.

PWB-PLO, Layout of Base PLO
    All of the components in the schematic are located in this Layout.  When the schematic is modifed, the components on the PWB will be modified.  The pads for missing components will remain.  This is the master artwork for the PWB and is used to order the PWB from Express.
    Revision A changes the pad sizes for the electrolytic capacitors so that ceramics can be used as alternate parts.
    Revision B added C48.

SKPWB-PLO, Schematic of Base PLO
    This is not a working schematic.  It is used to show the possible components for the Base PLO PWB.  Every component in the schematic has a pad placement on the PWB.